Methods and apparatus for selective stiffness of vehicle suspension

ABSTRACT

A method and apparatus for an adjustable suspension system for a vehicle comprises at least one strut. In one embodiment, the stanchion (or slider) is non-uniform with a major and minor circumferential stiffness and is adjustable relative to a fore and aft axis of the vehicle in order to provide a differing amount of stiffness relative thereto. In another embodiment, a portion of the stanchion is circular and a reinforcement is annularly disposed therearound with axial retention formations, The reinforcement has a non-uniform circumferential characteristic and is rotatable relative to the fore/aft axis of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 12/623,788, filed Nov. 23, 2009, which claims benefit of U.S.provisional patent application Ser. No. 61/117,090, filed Nov. 21, 2008,and U.S. provisional patent application Ser. No. 61/117,466, filed Nov.24, 2008. Each of the aforementioned related patent applications isherein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the invention generally relate to methods and apparatusfor use in vehicle suspension. Particular embodiments of the inventionrelate to methods and apparatus useful for structural reinforcement ofsuspension components.

Description of the Related Art

There are many types of vehicles that use suspension components forabsorbing and dissipating energy imparted to the vehicle by the terrainover which the vehicle travels. Bicycles and motorcycles, particularlythose designed for off road use, are used herein as examples ofvehicles. The front fork of a bicycle or motorcycle most often includesthe front suspension component of that vehicle.

Among riders and users (e.g., tuners, mechanics, designers) there is noconsensus on fork chassis stiffness (resistance to flexing) requirementsfor off road motorcycles. Supercross (i.e., stadium style motocross)courses are generally smoother and are packed with manmade obstaclesrequiring precision and timing to negotiate them properly. The precisionneeded in supercross leads the riders to choose stiffer, more precisesteering fork chassis. Professional supercross riders might, forexample, prefer large diameter forks for supercross races. Outdoormotocross is generally very fast with a mix of man made and naturalterrain obstacles. Outdoor motocross courses can get very rough.Professional outdoor motocross riders might, for example, prefer smallerdiameter, less rigid, fork chassis to allow some compliance through flexof the front fork system. Top level youth riders also differ amongstthemselves on fork chassis stiffness. Larger and more aggressive ridersmay look for more rigid fork systems. Lighter, smoother riders mayprefer some flex in their fork system to provide more compliance.

Vehicle suspension systems typically include structures that must resistforces tending to bend and/or twist those structures. That means thatthe structures need to be designed structurally to properly handleanticipated loads. In many applications it would, however, be desirableto selectively adjust the reinforcement of the suspension to suit theneeds of a particular user, the characteristics of the terrain to betraversed or both. What is needed is a structural reinforcement for asuspension component that is capable of being adjusted or “tuned” by auser between configurations offering more reinforcement in a chosendirection and configurations offering less reinforcement in a chosendirection as desired.

SUMMARY OF THE INVENTION

A method and apparatus for an adjustable suspension system for a vehiclecomprises at least one stanchion for receiving a slider. In oneembodiment, the stanchion or slider is non-uniform with a “major”stiffness and a “minor” stiffness axis and is adjustable relative to anup and down axis of the vehicle in order to provide a differing amountof suspension stiffness. In another embodiment, a portion of thestanchion is circular and a substantially longitudinal reinforcementportion is annularly disposed therein or around, or partially therein oraround with axial retention structures, The reinforcement is non-uniformcircumferentially and is movable relative to an up-down axis of thevehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features can be understoodin detail, a more particular description of that, briefly summarizedabove, may be had by reference to embodiments, some of which areillustrated in the appended drawings. It is to be noted, however, thatthe appended drawings only illustrate embodiments of this invention andare therefore not to be considered limiting of its scope, for theinvention may admit to other equally effective embodiments.

FIG. 1 is a side view of a motorcycle showing a front suspension system.

FIG. 2 is a section view showing one embodiment; FIG. 2A is a sectionaltop view of FIG. 2, taken through a line 2A-2A.

FIG. 3 is a drawing illustrating a major and minor axis of an ellipticalshape.

FIG. 4A is a section view showing an alternative embodiment.

FIG. 4B is a section view of FIG. 4 taken through a line 4B-4B and FIG.4B FIG. 4C is a section view taken through a line 4C-4C.

FIG. 5A is a top view showing an alternative embodiment of anon-circular or non-round cross section of a stanchion.

FIG. 5B is a side view of a reinforcement having a substantially uniformwall thickness with a non-uniform modulus or stiffness distributioncircumferentially and FIG. 5C is a top view thereof.

FIG. 6 is a side view showing a reinforcement bar that engages an innersurface of a stanchion and FIG. 6A is a top view thereof.

FIG. 7 is a side view showing a reinforcement ring having reinforcementlobes disposed within a stanchion and FIG. 7A is a top view thereof.

DETAILED DESCRIPTION

Some embodiments disclosed herein provide a fork chassis that is tunablefor stiffness. One aspect of stiffness where selective tuning isadvantageous is front (fore) to back (aft) and up to down (e.g., foreand aft in FIG. 2A as directions 34, 35 respectively, and up and downdirections in FIG. 1 and others as 34, 35 respectively) bending, or“beam,” stiffness. A modern motocross fork is made up of 5 primarystructural, or chassis, elements.

1. the lower/inner tube set (right and left sides of front wheel)commonly referred to as the sliders

2. the upper/outer tube set (telescopically engaged with the sliders)commonly referred to as the stanchions

3. the lower triple clamp

4. the upper triple clamp

5. the steering tube

While the examples herein may often be described in reference tomotorcycle or bicycle forks, the elements disclosed herein are suitablefor use on a wide variety of vehicles and respective suspension systems.

Referring also to a fork as shown in U.S. Pat. No. 4,878,558, the mainstructural element defining the front to back stiffness in the abovedescribed motocross front fork is the stanchion tube set (note would bethe slider tube set in an inverse fork set up). The region with thebiggest affect on front to back (e.g., FIGS. 2A and 4C—34, 35) stiffnessis the region below, through, and/or above the lower triple clamp (the“critical region”). It is noteworthy that some forks are essentiallyinverted from the above description in that the sliders are held withinthe triple clamp and the stanchions telescopically mounted below thesliders and thereby straddle the front wheel and engage with the frontaxle. The elements disclosed herein are equally suitable for use oneither of the aforementioned fork configurations as well as othersuspension configurations.

U.S. Pat. No. 4,878,558, assigned to Honda Giken Kogyo Kabushiki Kaishaand incorporated herein by reference in its entirety, describes anembodiment of a motorcycle fork and corresponding damage preventioncovers for the inner tubes 9. That patent describes (and FIG. 1 hereinshows by corresponding numbers) the stanchions as “outer cases 8” andthe sliders as “inner tubes 9.” That patent further describes the upperand lower triple clamps as “upper and lower brackets respectively as 7(or 20 FIG. 1 herein), 7.” It also refers to the steering tube as a“steering handle rotary shaft 6.”

U.S. Pat. No. 7,425,009, assigned to Showa Corporation and incorporatedherein by reference in its entirety, describes the upper and lowertriple clamp as the “upper bracket 15” and the “under bracket 16”respectively. It refers to the steering tube as the “steering shaft (notshown).” The stanchions are referred to as “outer tubes 13 and 13”' andthe sliders are referred to as “inner tubes 14 and 14′.” The Showapatent describes disc brake forces generated (directions shown in FIG.3) on the disc side of the fork that are asymmetric in relation to theright and left sides of the fork. The Showa patent proposes a uniformincreased thickness of the inner tube 14′ of the disc side fork toincrease stiffness of the brake side fork leg.

Other patents have dealt in various ways with various aspects ofincreased fork stiffness. U.S. Pat. No. 6,352,276, assigned toMarzocchi, USA, Inc. and incorporated herein by reference in itsentirety, refers to a steering tube as a “stem tube 14”, a lower tripleclamp as a “crown 12” and a pair of “struts 16” corresponding tostanchions (because the '276 patent does not include suspension thereare only stanchions and no sliders).

U.S. Pat. No. RE38,669 having inventors Darrell Voss and Gary Klein andbeing incorporated herein by reference in its entirety, refers to thelower triple clamp as “crown 6-3” and “stanchion tube 8-1 L.” U.S. Pat.No. 5,908,200, assigned to Answer Products Inc. and incorporated hereinby reference in its entirety, refers to the steering tube as “steeringtube 12,” lower triple clamp as “crown 14,” stanchions as “lower tube24” and the sliders as “upper tube 26.” Noteworthy in the preceding twopatents is that while bicycle forks may include an upper and lowertriple clamp, they often include only the lower clamp or “crown.”

U.S. Pat. No. 6,893,037, having inventor Mario Galasso and incorporatedherein by reference in its entirety, refers to “steer tube 4,” “crown5,” “stanchions 6” and “slider 10” as the respective parts of the fork.

It is noted that, regarding vehicles that employ fork type frontsuspension; while mounting stanchions to the steering head is quitecommon particularly on motorcycles, certain types of vehicles still useforks having sliders mounted to the steering head with the stanchionsattached to the suspended wheel. The fork reinforcement embodimentsdisclosed herein are equally well suited for use with stanchions orsliders as mounted to a vehicle steering head. Reference herein tostanchions or sliders is for illustrative purposes only. Also noteworthyis that some suspension “forks” are asymmetrical and comprise only onestanchion/slider set, held by one triple clamp set and traversing onlyone side of a suspended wheel. The embodiments herein a well suited foruse on only one stanchion/slider pair. Further, embodiments herein aresuitable for use with vehicle forks having no stanchion/slider pairingsuch as that shown in U.S. Pat. No. 6,145,862, which patent isincorporated herein, in its entirety, by reference. That '862 patentincludes a bicycle fork, that while suspended in a head tubearrangement, comprises no moving parts in the fork struts. Embodimentsdisclosed herein may nonetheless be useful in selectively stiffening orreducing stiffness in single piece forks. Additionally, as shown in U.S.Pat. No. 4,170,369, which patent is incorporated herein, in itsentirety, by reference, a “fork” need not comprise more than a singlestrut (noting that each of a stanchion and a slider is a “strut” andtogether the form a telescopic “strut” or strut assembly). Embodimentsherein may nonetheless be used in conjunction with such single struttype forks whether the single strut includes a suspension component ornot.

In one embodiment, shown in FIG. 1 of the present application, thestanchions 8 are held in the lower triple clamp 7 and the upper tripleclamp 20. Referring to FIGS. 2 and 2A, while the inner diameter of thestanchions 8 is circular, at least a portion of the length of thestanchions has an elliptical outer surface. As shown in FIG. 2A thestanchion 8 is positioned in relation to lower triple clamp 7 such thatthe major elliptical axis (refer to FIG. 3) of the stanchion 8 issubstantially aligned with the forward 34 and aft 35 directions of thebicycle or motorcycle. The lower triple clamp parts 7 and 30 engage toform a substantially circular clamped region. The split bushing 31, 32adapts the elliptical outer surface of the stanchion 8 to be clamped bythe circular inner surface of lower triple clamp 7. The split bushing31, 32 is scarf cut 33 in two places (or cut in any other suitablemanner) at approximately 180 degrees. That allows the split bushing31,32 to tightly transfer clamping force from the triple clamp 7 to thestanchion 8 by mitigating substantial part tolerance issues that mightotherwise interfere. In one embodiment the bushing comprises asubstantially incompressible elastic material (e.g. rubber, urethane)and will transfer clamping force there though by means of an iso-staticpressure created therein by the clamping force (based on bulk modulus ofthe material). As such a scarf cut is not always necessary. With thestanchion 8 and split bushing 31, 32 in place, the triple clamp 7, 30 istightened by means of the triple clamp bolts as shown.

In one embodiment the cross section for the stanchion tube 8 in thecritical region is non round. One example of a suitable non-circular ornon-round cross section is shown in FIG. 5A. The stanchion 8 includes a“lobe” or beam web 100 (running axially along a length of the stanchionbut not shown) which enhances axial bending stiffness of the stanchion 8along plane 105 (plane 105 shown as line 105 and extending into and outof the page). The lobe may be any suitable cross sectional shape and maybe located circumferentially at a single zone or the stanchion maycomprise a plurality of lobes located for example at 180 degrees orother suitable locations for enhancing selected bending stiffness of thestanchion 8. For purposes of this description the non round crosssection may be elliptical (referring to FIG. 3) although practically itmay be any other suitable cross section (i.e., consistent with selectivereinforcement). The raw material for the stanchion 8 may be a tube withround ID and elliptical OD. Below the axially, or lengthwise, lowestdesired elliptical section of the tube, the tube may be machined to havea round OD in order to reduce weight where the elliptical cross sectioncontribution is not needed. Above the upper most elliptical crosssection, the tube may include a round OD, if desired, so that theinterface with the upper triple clamp 20 is simpler. Referring to FIGS.2 and 2A, a split shim 31, 32 is mounted in the lower triple clamp 7,30. The OD of this shim 31, 32 is round. The ID of this shim 31, 32 iselliptical and fits over the elliptical OD of the stanchion tube 8. Inessence, this composite cross section of stanchion 8 and shim 31, 32results in a round OD interface with the lower triple clamp 7, 30. Theround, or circular, interface helps facilitate ease of rotation (e.g.adjustment) of the stanchion relative to the clamp when altered forkstiffness characteristics are desired. When the major axis (note theterm “major axis” herein refers not only to the dimensionally largercross sectional axis but also to any axis including the plane ofincreased stiffness 105) of the stanchion 8 is aligned parallel to thecenter plane 34, 35 of the vehicle (e.g. motorcycle, bicycle), the forkwill be in its' stiffest front to rear setting. That is consistent withcross sectional moment of inertia calculations and beam stiffnesscalculations presuming the major axis to comprise the web of a crosssectioned beam. It is noteworthy that the cross section of the stanchionmay vary and include many suitable shapes or combinations thereof (e.g.,rectangle, I beam web). The “web” or cross sectional extension may existon only one side of the stanchion 8 thereby forming in one embodiment a“tear drop” shaped cross section.

In one embodiment, when stanchion 8 is rotated approximately 90 degreesrelative to the triple clamp 7, 20 such that the minor axis of thestanchion 8 is aligned with the center plane 34, 35 of the motorcycle,the fork will be in its' least stiff front to rear setting. Laseretching datum marks, or other suitable marking may be provided on thelower triple clamp 7, 30 and on the outside of the stanchion 8 to allowthe rider to readily line up the major or minor axes in the desiredorientation (e.g., front to rear stiff or front to rear flexiblecorresponding with the major and minor axis alignment respectively withplane 34, 35). As is shown the triple clamp 7, 30 and 20 may be loosenedand the rider/user can rotationally orient the major axis of thestanchion 8 in line with front rear vehicle plane 34, 35 for maximumfork stiffness or laterally 36 for maximum fork flexibility or atorientations in between for corresponding intermediate stiffness.

In one embodiment, and referring to FIGS. 4A-4C, stanchion 8 (or sliderif inverse fork arrangement) has a circular inner diameter and acircular outer diameter. The outer diameter of stanchion 8 is scribedwith grooves 41 at intervals along its length over a region of desiredstanchion support. In between the grooves 41 are circumferential raised(relative to the groove depth—e.g. full stanchion OD) diameter portions45 (optionally 41/45 may comprise a selected thread form). Fitted aroundthe exterior of the stanchion 8 axially along the length of a region ofdesired selectable enhanced support, is reinforcement 40. For initialinstallation reinforcement 40 is spread, at scarf cut 46, to fit overstanchion 8. Reinforcement 40 may comprise two cuts at suitable relativeangles, such as 180 degrees (in other words reinforcement 40 maycomprise two pieces), thereby avoiding any need to flex thereinforcement 40 during installation. Reinforcement 40 has spaced innergrooves 44 and smaller intervening ID portions 43 that engagerespectively with raised diameter portions 45 and grooves 41 of thestanchion. Once the reinforcement 40 is installed on stanchion 8 it isrotatable there about. With the triple clamp 7, 30 (and 20 ifreinforcement extends that far) loose the major axis of thereinforcement can be selectively aligned with the vehicle front/rearplane 34, 35 to provide maximum fork stiffness or with lateral plane 36to provide minimum stiffness. It may also be aligned at intermediatepositions. With the reinforcement 40 in the desired orientation, thetriple clamp 7, 30 is tightened around the reinforcement 40 which inturn tightens around stanchion 8 thereby retaining the stanchion and thepreferred orientation of the reinforcement 40. As shown in FIG. 4B, theouter surface 49 of the reinforcement 40 is circular in the axial regionwithin (i.e. corresponding to the length of) the triple clamp 7, 3D. Asdemonstrated by FIG. 4C, the reinforcement 40 has an elliptical outersurface at axial locations on either side of the triple clamp 7, 30. Theinner surface 49 of the triple clamp 7, 30 is circular so as tosubstantially engage the circular outer surface 49 of the reinforcement40 (within the triple clamp). The engaged circular surfaces 49facilitate rotation of reinforcement 40 within the loosened triple clamp7, 30 and gripping retention of reinforcement 40, by the tightenedtriple clamp 7, 30 in any selected relative rotational orientationbetween the reinforcement and the clamp. Additionally, the innersurfaces of the reinforcement 40 are substantially circular to engagethe circular outer surface of the stanchion 8. The engaged grooves 41,43 and 44, 45 provide axial lengthwise shear area thereby transferringbending forces between the stanchion 8 and the reinforcement 40 (asinter-part surface shear and hence enabling the reinforcement to aid instiffening the stanchion). Note that other suitable axial shear transfermechanisms may be employed such as, for example, axially spaced clampswhere inter-part friction is the shear transfer mechanism or throughbolts where headed bolts are disposed in holes though the reinforcement40 and threaded into the stanchion (alternative holes threaded intostanchion at 90 degrees to facilitate rotation and retained orientationof the reinforcement 40. Depending on the axial length of the criticalregion (e.g. desired engagement length between reinforcement 40 andstanchion 8) addition axially spaced clamps may be preferred. Suchclamps may be placed around the reinforcement at selected axiallocations to retain the reinforcement 40 grooves 44 in contact with theraised portions 45 of the stanchions. Clamps and grooves may be usedseparately or in combination for added shear force transfer.

One embodiment comprises providing an “add on” reinforcement orstiffening element 40 that may be added to (and fixed to) an exterior ofa stanchion tube 8 of a fork chassis. In one embodiment the stiffener orreinforcement 40, when in use to enhance fork stiffness, is mounted onthe front facing 34 side of the fork and is mounted to the stanchiontubes 8 below the lower triple clamp 7, 30 and above the lower tripleclamp 7, 30. Optionally the stanchion 8 can provide mounting provisionsfor the stiffener 40 to directly bolt/mount to the tube 8, or secondaryclamps (not shown) may be used to mount around the reinforcement 40 andstanchion 8 to affix the stiffening element 40 to the front side 34 ofthe fork. The stiffening element 40 can be produced from a variety ofmaterials, including carbon fiber reinforced composite, injection moldedplastic, stamped/formed aluminum, metal matrix composite, work hardenedand heat treated brass, steel, titanium, magnesium, or any suitablematerial or combination thereof. It is noteworthy that reinforcement 40need not circumvent the stanchion 8 and in fact may only be on theforward 34 side of the stanchion 8 (in other words the reinforcement 40may be embodied as a “half shell” spanning only 180 degrees of acircumference or less, or more). Such reinforcement 40 would look likethe left half of that stiffener 40 as shown in FIG. 4A and may be usedin conjunction with a retaining mechanism such as for example axiallyspaced clamps, or bolts (e.g. bolted directly to the stanchion orslider) along a length of the critical region of desired enhancedstiffness to retain the reinforcement 40. The reinforcement 40 need nottraverse the triple clamp 7 and may be only above or below (or both)that clamp 7. In one embodiment the reinforcement 40 is retained at anupper end under the upper triple clamp and at a lower portion under thelower triple clamp. In one embodiment (e.g. a single crown bicycle fork)the reinforcement 40 extends below the crown or single lower fork legclamp and supports a portion of the fork leg there below. An axiallyspaced bolt hole pattern may be built into the stanchion on a forward 34or rear 35 face and on a lateral face 36 such that a bolt onreinforcement may be moved from front to side with a bolt arrangement.Alternatively a front 34 bolt on reinforcement 40 and the reinforcement40 itself may merely be removed from the fork leg when more forkflexibility is desired. The reinforcement may be located on thestanchion 8 or the slider or both. It may be placed only between theupper and lower triple clamp and in one embodiment does not engage thetriple clamps at all. The reinforcement 40 may be used on any of avariety of beam loaded (e.g. beam supported) vehicle suspension members.

In one embodiment, referring to FIGS. 5B and 5C, the reinforcement 40comprises a substantially circular tube 80 having a substantiallyuniform wall thickness (e.g. no major or minor dimensions) where thewall has a non-uniform modulus (stiffness) distributioncircumferentially. Generally, as described herein, non-uniform modulusdistribution may result from: 1) dimensional variations; materialvariations (including local modulus and/or strength characteristics); or3) suitable combinations of material and dimensional variations. In oneembodiment the reinforcement 40 comprises a material or materialcombination resulting in varying degrees of axial (e.g. lengthwise)bending stiffness at varying locations circumferentially. In oneembodiment a carbon fiber filled composite reinforcement 40 comprises acircumferential zone 85 of, for example, approximately 90 degrees (e.g.a quadrant) that is axially reinforced with a higher modulus carbonfiber 90 than the remaining circumferential structure of thereinforcement 40. Such reinforcement results in a zone of high stiffness85. Such a zone may comprise, for example, 90 degrees, 180 degrees, 45degrees or any suitable zone angle (or no particular angle per se) forenhancing bending stiffness in a selected zone (and hence orientation).The zone may comprise a continuous reinforcement fiber (e.g. axial 96 ororientated 95), chop random fiber, granular, oriented short, fabric, orany suitable filler for increased structural stiffness. In oneembodiment the tube 80 includes a high stiffness zone that comprises abase material having a property of high modulus relative to the basematerial of the remainder of the tube 80. In one embodiment the tube 80is made from a material having varying states of stiffness around itscircumference. Such varying state stiffness zones may be created forexample by selective heat treating. In one embodiment a high strengthtube is manufactured having a first stiffness and a zone of that tube isheat treated, using for example localized induction heating, (with acorresponding modulus change such as multiphase brass) leaving a highstiffness zone in the non-annealed area. In one embodiment (not shown)two such high modulus reinforced zones are positioned diametricallyopposite one another, for example at 180 degrees apartcircumferentially. In one embodiment the reinforcement 40 comprises asuitable combination of selective high modulus construction orreinforcement and a major and minor dimension in cross sectional profile(e.g. non-circular shape plus coincident high stiffness zone. It isnoteworthy that the circular cross section reinforcement 40 as describedherein would be suitable for use as described herein without anyaccommodation for non circular cross section in any clamping mechanism.In one embodiment, referring to FIGS. 5B and 5C, a “window” 98 ofmaterial is removed or reduced from a wall or walls of the tube 80corresponding to a zone(s) of reduced stiffness (thereby leaving azone(s) of high stiffness). Shapes, materials and concepts disclosedherein regarding either stanchions (sliders) or stanchion (slider)reinforcement members are described in reference to one or the other butthe reinforcement and stiffness zone creation mechanisms disclosedherein are, for the most part, equally well suited to use directly witha stanchion or slider, or as part of a stanchion or slider reinforcementmember.

In one embodiment, the reinforcement is part of the fork leg assembly.Referring to FIGS. 6 and 7, the reinforcement 40 is inside, for example,the stanchion 8. Note that directions 34 and 35 are fore and aftrespectively as related to the top views of each Figure (6A and 7A). Inone embodiment (referring to FIGS. 6 and 6A) reinforcement 40 comprisesone or more “bars” which engage an inner surface of the stanchion 8 bymeans of dovetail form slots 210 therein. The reinforcement bars 40 areretained radially (e.g. from falling inward) and rotationally, inselected orientation, by the dovetail slots 210 and retained at a lowerend by circumferential shoulder 220 within the stanchion 8. The bars 40may be retained at an upper end by a top cap (not shown) of thestanchion 8. When one or more bars 40 are in place in a plane residingin the fore 34/aft 35 direction, they enhance the stiffness of thestanchion along the length in which they are disposed. When morestanchion flexibility is desired, a user may merely remove thereinforcement bar(s) 40.

Referring to FIGS. 7 and 7A, a reinforcement ring 200 comprisesreinforcement lobes 40. The ring 200 and its lobes 40 are disposedwithin the stanchion 8 and are retained axially upon an inner shoulder220. The reinforcement ring 200 may be axially retained at an upper endby a stanchion top cap (not shown). The reinforcement ring may berotated within the stanchion to alter the stiffness of the stanchion inthe fore 34/aft 35 direction. The outer surface of the ring 200 and theinner surface of the stanchion 8 may be inter-engagably splined along atleast a portion of interface 230 so that the spline engagement (e.g.axially oriented “teeth” such as fine gear teeth) retains selectedorientation between the ring 200 and the stanchion 8. In order to changethe orientation, the ring 200 may be withdrawn axially upward (followingremoval of the stanchion top cap for example) until the splines at 200are no longer engaged. The ring may then be rotated and re-orientatedconsistent with the indexing of the splines and replaced within thestanchion (the top cap or other retainer may then be replaced).

While embodiments herein have been described in reference to frontvehicle suspension and specifically vehicle “forks” it is noted that theconcepts hereof including embodiments of reinforcement 40 are suitablefor use with other suspension linkages such as rear (e.g. motorcycle,bicycle) swing arms, frame struts and other structural vehicle memberswhere user selectable stiffness is desirable. In many circumstancescontemplated herein, the terms fore 34 and aft 35, as used herein, alsoapply to “up and “down” respectively because the plane, for example 105,that extends front (fore) and back (aft) also extends up and downrelative to a vehicle. That is appropriate because vehicle suspensionand linkage often operate substantially in the plane perpendicular tothe surface being traversed by the vehicle (e.g. up and down) andbending forces encountered by the suspension derive from forcecomponents in the “up and down” directions.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the scope thereof, and the scope thereof is determined bythe claims that follow.

The invention claimed is:
 1. A suspension for a vehicle comprising: astrut assembly including a first and a second longitudinal reinforcementmember, the first longitudinal reinforcement member disposed within thesecond longitudinal reinforcement member and the longitudinalreinforcement members are rotatable between a first position in whichthe strut has a first stiffness in a plane substantially aligned with anup and down and a fore and aft direction relative to the vehicle and asecond position in which the strut has a second stiffness, in thedirection of the plane, the second stiffness being lower than the firststiffness; and a selectively engageable orientation retainer forselectively retaining the longitudinal reinforcement members in thefirst position and the second position.
 2. The suspension system ofclaim 1, wherein the second reinforcement member is non-circular with amajor and a minor dimension and the first stiffness in the firstposition results from the major dimension being substantially alignedwith the plane.
 3. The suspension of claim 1, wherein a first portion ofthe second reinforcement member includes a circular outer surface and asecond portion of the second reinforcement member includes anon-circular outer surface, the first portion defining an axial regionof the second reinforcement member retained by the orientation retainerin the first and second positions.
 4. The suspension of claim 1, whereinthe first reinforcement member is a stanchion, the stanchion including aplurality of grooves on an exterior thereof, wherein the secondreinforcement member includes a plurality of grooves formed on aninterior thereof for mating with the plurality of grooves on thestanchion.
 5. A method for altering a stiffness of a vehicle suspensioncomprising: rotating a first and a second longitudinal reinforcementmember from a first position to a second position to enhance suspensionstiffness in a plane substantially aligned with a fore and aft directionand an up and down direction relative to the vehicle, wherein the firstlongitudinal reinforcement member is disposed within the secondlongitudinal reinforcement member; and selectively retaining thelongitudinal reinforcement member in the first and second position. 6.The method of claim 5, wherein an orientation retainer engages to thesecond longitudinal reinforcement member to retain the longitudinalreinforcement members in the first and second position.
 7. An apparatusfor selective stiffness of a vehicle suspension, comprising: a stanchionfor receiving a slider, the stanchion having an outer surface in atleast one area including axial retention formations formed thereon; areinforcement for at least partially surrounding the stanchion, thereinforcement having a set of mating axial retention formations formedon an interior thereof whereby the formations substantially preventaxial movement of the stanchion relative to the reinforcement; and aclamp for clamping the reinforcement to the stanchion, wherein thereinforcement is rotationally movable about the stanchion when the clampis unclamped.
 8. The apparatus of claim 7, wherein the axial retentionformations and mating formations comprise a plurality of complementarygrooves on the stanchion and the reinforcement.
 9. The apparatus ofclaim 7, wherein a first portion of the outer surface of thereinforcement is non-circular, a second portion of the outer surface ofthe reinforcement is circular, and the second portion is adjacent to theclamp.
 10. The apparatus of claim 9, wherein the mating formationspermit rotation between the reinforcement and the stanchion.
 11. Theapparatus of claim 10, wherein the rotation permits a major axis of thefirst non-circular portion of the reinforcement to be arranged between aposition parallel to a major axis of the vehicle and a positionperpendicular thereto.